Automatic speed-changing attachment for gear-cutting machines.



J. P. JOHNSON. AUTOMATIC SPEED CHANGING ATTACHMENT FOR GEAR CUTTING MACHINES.

APPLICATION FILED DEC. 13. I916. l 25%283v 3 SHEETS-SHEET I.

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Patented Jan. 22, 1918.

J. P. JOHNSON. AUTOMATIC SPEED CHANGING ATTACHMENTFOR GEAR cunmc MACHINES.

APPLICATION FILED DEC. [3, I916. L fi4 fifi3v Patented Jan. 22, 1918.

3 SHEETS-SHEET 2.

J. P. JOHNSON.

AUTOMATIC SPEED CHANGING ATTACHMENT FOR GEAR CUTTING MACHINES. APPLICATION FILED DEC. 13. 1916. 1

mamas, Patented Jan. 22,1916

3 SHEETS-SHEET 3.

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,JAMESP. JOHNSON, 0F CLEVELAND, OHIO.

AUTOMATIC SPEED-CHANGING ATTACHMENT FOR GEAR-CUTTING MACHINES.

Application filed December 13, 1916.

T 0 all whom it may concern:

Be it known that I, Jim ins P. JOHNSON, a citizen of the United States, residing at Cleveland, in the county of Cuyahoga and State of Ohio, have invented a certain new and useful Improvement in Automatic Speed-Changing Attachments for Gear-Cutting Machines, of which the following is a specification.

This invention relates to mechanism adapted to be attached to a gear cutting machine of a certain well known type, that cooperates with the mechanism of said machine and automatically changes the speed at a desired period during the cutting of the gear. In the formation of gears for high grade work such as automobiles and other machines where perfection of mesh is particularly desirable and sought for, with stillness, smooth running, durability and other objects in view, the teeth are first roughed out on the gear blanks. After the roughing stage of the process, the teeth are finished in gear cutting machines. The present invention is particularly applicable to a certain machine of this character, known as the Fellows gear cutter. In perfecting the gears with this particular machine, the teeth are first given a primary cut and afterward a finishing out. After the primary out, which requires one complete revolution of the gear, the mechanism is automatically adjusted for the final or finishing cut.

Heretofore in the operation of machines of this type the same predetermined speed has been maintained in both the primary and finishing stages, owing principally to the fact, that while there is a signal that announces the completion of the gear, there is no provision made for indicating the shift from the primary cut to the finishing out. By careful observation an operator can determine when the change takes place, but as it is customary for one attendant to operate a battery of several machines, it would be difficult for him to note the exact moment of shift in each machine, in fact the auto matic adjustment is provided to overcome this difficulty.

It has been found that satisfactory results may be obtained by operating the machine at a more or less high rate of speed on the primary cut and reducing the rate for the finishing out. By so doing the desired result of perfection of gear is obtained with a considerable per cent. of increase in Specification of Letters Patent.

Patented J an. 22, 191%.

Serial No. 136,635.

production. For example, if there is a ratio of two to one between the driving and driven step pulleys, and it is found that fourteen minutes is the proper time for one complete revolution of the gear on the finishing cut, the machine is timed so as to get this result on the low speed. As the shift from the primary to the finishing operation is auto matic, the same speed is maintained in practice with the machines as heretofore operated, while the primary cut could be accomplished, without detriment to the gear, on the high speed, or with a seven minute revolution. In order to obtain the increased per cent. of production the shifting from high to low speed at the proper period must necessarily be automatic; therefore among the objects of the present invention is the provision in certain gear cutting machines of means for automatically changing the speed of operation between the primary and finishing stages of the process, and thereby increasing the efficiency of the machine. A further object of the invention is to provide simple, durable and reliable means for the purpose set forth, that can be readily -.:ttached to a certain type of mechanism known as the Fellows gear cutting machine, and co-acting with the operating mechanism of said machine produce the desired result. With these objects in view the invention consists in the construction, combination, and arrangement of the parts hereinafter described and pointed out definitely in the annexed claims.

To facilitate the explanation of the invention, the accompanying drawings are made a part of the specification and similar characters of reference are employed to designate similar parts. In the said drawings Figure l is an outline elevation of a Fellows gear cutter, showing the improved attach ment as applied. Fig. 2 is an end view on an enlarged scale, of a fragment of the mic chine, showing the improvement and the relative position of elements when o 'ierating on high speed. Fig. 3 is a view in direction of arrow (1 in Fig. 2. Fig. 4: is a plan view, and Fig. 5 illustrates the relative position of certain of the elements when operative on low speed.

In the general operation of the machine to which this improvement is particularly applicable, the rough gear 1 to be cut, first fixed in a suitable arbor, and the cutting. tool 2 is then adjusted to the proper iii) position for s arting the primary cut; The co-acting operation of the several elements of the machine imparts a reciprocating motion to the tool 2 and a rotary motion to said tool and to the gear 1. mechanism is also provided for feeding the tool into the gear. The speed of operation is controlled by the driving and driven step pulleys 3 and 4t, respectively. The mecha nism for performing the above mentioned functions is perfected and embodied in the machines in present use; therefore a detailed analysis of the construction is, not deemed necessary except so far as its relation and cooperation with the improvement is concerned.

During the period of the full primary cut the gear 1 makes one complete revolution, and through the action of certain intermediate mechanism the gear 5 and member 6 also perform one complete revolution. At the termination of the primary cut an automatic adjustment places the elements in po sition for the finishing out, and this operation proceeds without interruption or stoppage of the machine.

The present invention provides for the automatic changing of speed at the same time that the change is made from the primary to the finishing operation, high speed being employed for the first and low speed for the final function. This is realized by the construction, arrangement, and cooperation of the mechanism which will now be described.

In the embodiment of the invention as illustrated, a bracket 7 is attached to the body of the machine, and mounted in said bracket is a shaft 8. Keyed or otherwise made fast to the shaft 8 are the arms 9, 10, and 11. The arm 9 is provided with an actuating member 12, whereby the shaft 8 can be rocked. Pivotally connected with the free end of the arm 9, or the end remote from the shaft 8, is a depending bar 13. A branch 14 of the bracket 7 is provided with a. slot 15 and a cross pin 16. The bar 13 extends through the slot 15 and is provided with an incision or notch 17. hen the shaft 8 is rocked by the actuating member 12 in the direction of arrow Z) the bar 13 is raised and the notch 17 engages the cross pin 16 through the influence of the spring 18.

A high speed belt 19 and a low speed belt 20 are provided and are adapted to cooperate with the driving and driven step pulleys. These belts are normally loose on their pulleys. The arm 10 is provided at its free end with an idler 21, and the arm 11 with an idler 22. The arms 10 and 11 are so positioned on the shaft 8 that when said shaft is in the position shown in Fig. 2, with the itch 17 engaging the pin 16 the idler E22 tightens the belt 19 and puts the Timed feed 7 boss is so located that at the instant of starting the'finishing out it contacts the roller 23 and the said roller riding over the boss releases the notch 17 from the pin 16. With the bar 13 thus released, the shaft 8 is automatically rocked by the influence of a high tension spring 25 which is connected with the arm 9 and the member 14. This action causes the idler 22 to leave the belt 19, while idler 21 tightens belt 20, thereby bringing the low speed into operation. During the operation of the high speed the low speed belt is loose, or inactive, and during the low speed operation is similarly inactive.

The low speed is maintained during the interval of the finishing cut, or until the signal announces the completion of the gear. The machine is then stopped for the purpose of removing the finished article and the insertion of another roughgear. Before starting the machinefor another operation the shaft 8 is rocked manually through the medium of the actuating member '12,

the notch 17 engaging the pin 16, and the high speed brought into action by the idler 22 and belt 19, as before described.

The embodiment of the invention as shown and described has been reduced to practice and is a simple'and practical construction, but there are other mechanical constructions involving similar principles of operation, or performing the same functions in a similar manner, that maybe employed without de} parting froni the spirit of the claims. It will be understood therefore that the invention is not confined to this specific construction, combination, and arrangement of ele ments only so far as limited by the scope of the following claims. 7

What I claim and desire to ters Patent is:' I,

1. In speed changing mechanism for gear cutters the combination of feed mechanism; driving means; speed controlling elements secure by Letconneeted with said driving means; a rocker.

member; means for actuating said rocker. member, said means operating in timed relation to the feed mechanism garms rigidly connected with said rocker member and extending therefrom at different angles; idlers mounted on said arms which alternately en gage and disengage the speed controlling elements.

j 2. In speed changing mechanism for gear. cutters the combination of differentialspeed controlling elements; timed cutter operative means; a rocker member; arms rigidly conthe high'speed belt lltl nected with said rocker member and extending therefrom at different angles; idlers mounted on said arms, said idlers so arranged that they will alternately engage the differential speed controlling elements; means connected with said rocker member for actuating same, said means cooperating with the timed operative mechanism Where by'said rocker is actuated and the speed changed at determined periods in the cutting of the gear.

3. Mechanism adapted to be attached to a gear cutting machine and to cooperate with the feed and driving mechanism of said machine for changing the. speed at a determined period in the cutting of a gear, comprising differential speed controlling elements, a rocker member having arms extending therefrom at different angles, idlers mounted on said arms that alternately engage the difierent speed controlling elements of the driving mechanism, a bracket attached to the body of the machine, a bar connected with the rocker member for engagement with the bracket and thereby retain said rocker with one idler in engagement, means cooperating with the feed mechanism for disengaging the bar from the bracket at a certain determined period, and means connected with the rocker member for disengagement of the one idler and engagement of the other when said bar is released.

a. In mechanism for the purpose set forth, feed mechanism and driving mechanism embodying differential speed pulleys, belts connecting the driving and driven pulleys, said belts being loose on said pulleys, a rocker member mounted in permanent bearings, idlers carried by said rocker member and adapted for alternate engagement with the belts to thereby tighten same, a manually operative member attached to said rocker member, a bracket attached to the body of the machine, a bar connected with the rocker member for engagement with the bracket to thereby retain said rocker With one idler in engagement, means cooperating with the feed mechanism for disengaging the bar from the bracket at a certain period, and means connected with the rocker member for disengagement of the one idler and engagement of the other when said bar is released.

In an automatic speed changing device for gear cutting machines, the combination with the feed mechanism and differential speed pulleys. of high and low speed belts connecting said pulleys and loosely mounted thereon, a rocker shaft carrying arms provided with idler pulleys at their free terminals, said idlers adapted to alternately engage the high and low speed belts and thereby cause said belts to alternately become taut, an operating arm fast on said rocker shaft, a b acket attached to the body of the machine, an operating bar connected with the operating arm, means for engage ment of the operating bar with said bracket when the high speed belt is engaged with an idler, means connected and cooperating with the feed mechanism for releasing the operating bar from the bracket at a certain period of the cutting operatioi'i, and means for antomatically actuating the rocker member when said bar is released to thereby release the high speed. belt and cause an idler to engage the low speed belt.

6. In an automatic speed changing device for gear cutting machines, the combination with the feed mechanism and differential speed pulleys, of high and low speed belts coniiecting said pulleys and loosely mounted thereon, a rocker shaft carrying arms proridcd with idlers at their free terminals, said idlers adapted to alternately engage the high and low speed belts and thereby cause said belts to alternately become taut, an operating arm fast on said rocker shaft, a bracket attached to the body of the machine, an op erating bar connected with the operating arm, means for engagement of the operating bar with said bracket when the high speed belt is engaged with an idler, means connected and cooperating with the feed mechanism for releasing the operating bar from the bracket at a certain period of the cutting operation, means for automatically actuating the rocker member when said bar is released to thereby release the high speed belt and cause an idler to engage the low speed belt, and a manually operative member attached to the rocker member for reversing the automatic operation of said rocker.

7. In an automatic speed changing device for gear cutting machines, the combination with the feed mechanism and differential speed pulleys, of high and low speed belts connecting said pulleys and loosely mounted thereon, a rocker shaft carrying arms provided with idler pulleys at their terminals, said idlers adapted to alternately engage the high and low speed belts and thereby cause said belts to alternately become taut, an operating arm fast on said rocker shaft, a bracket attached to the body of the machine, a slotin said bracket and a pin bridging said slot, an operating bar connected with the operating arm and extending through the slot in the bracket, means on said operating bar for engaging the pin when the high speed belt is engaged with an idler, means connected and cooperating with the feed mechanism for releasing the operatingbar from the pin at a certain period, and mean for automatically actuating the rocker shaft when said bar is released to thereby release the high speed belt and cause an idler to engage the low speed belt.

8. In an automatic speed changing device for gear cutting machines the combination with the feed mechanism and differential speed pulleys, of high andv low speed belts connecting said pulleys and loosely mounted thereon, a rocker shatt carrying arms provided with idler pulleys at their free terminals said idler-s adapted to alternately engage the high and low speed belts and thereby cause said belts to alternately become taut, an operating arm fast on said rocker sh aft, a bracket attached to the body ot the machine a slot in said bracket and a pin bridging said slot an operating bar connected with the operating arm and extend ing through the slot in the bracket; means on said operating bar for engaging the pin uhen the high-speed belt is engaged with an idler, means connected and cooperating -with the feed u'iechanlsm of the machine for releasing the operatingbar from the bracket at a certain period, means for automatically actuating the rocker shaft when Said bar is released to thereby release the high speed belt and cause an idler to engage the low speed belt, and a manually operative member attached to the rocker shaft for reversing the automatic operation of said rocker.

JAMES P. JOHNSON.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of'i'atents Washington, D. G. 

